Fix TWI scan example
Fix TWI scan example

- Bitwise AND does not evaluate 1 or 0. For example
  checking the NACK bit as (aery::__twi_lsr & AVR32_TWI_SR_NACK_MASK) == 1
  is wrong. Has to be (aery::__twi_lsr & AVR32_TWI_SR_NACK_MASK) != 0.

denravonska/aery32,denravonska/aery32,aery32/aery32,aery32/aery32